Shampoo compositions comprising various combinations of detersive surfactant and conditioning agents are known. These products typically comprise an anionic detersive surfactant in combination with a conditioning agent such as silicone, hydrocarbon oil, fatty esters, or combinations thereof. These products have become more popular among consumers as a means of conveniently obtaining hair and skin conditioning and cleansing performance all from a single personal care product.
However, many shampoo compositions do not provide sufficient deposition of conditioning agents onto hair and skin during the cleansing process. Without such deposition, large proportions of conditioning agent are rinsed away during the cleansing process and therefore provide little or no conditioning benefit. Without sufficient deposition of the conditioning agent on the hair and skin, relatively high levels of conditioning agents may be needed in the personal cleansing composition to provide adequate conditioning performance. However, high levels of a conditioning agent can increase raw material costs, reduce lathering, and present product stability concerns.
Obtaining good deposition of a conditioning agent is further complicated by the action of detersive surfactants in the shampoo composition. Detersive surfactants are designed to carry away or remove oil, grease, dirt, and particulate matter from the hair and skin. In doing so, the detersive surfactants can also interfere with deposition of the conditioning agent, and both deposited and non deposited conditioning agent can be removed during rinsing. This further reduces deposition of the conditioning agent onto the hair and skin after rinsing, thus further reducing conditioning performance.
One known method for improving deposition of a conditioning agent involves the use of certain cationic deposition polymers. These polymers may be natural cellulosic or guar polymers that have been modified with cationic substituents. Selecting a polymer with sufficient charge density and molecular weight in combination with an optimized surfactant system results in sufficient deposition of conditioning agents. When the silicone in these higher deposition systems has a high internal phase viscosity some consumers notice performance tradeoffs in terms of reduced shampoo cleaning, conditioner buildup, and a reduction in volume of the hair style. A high internal phase viscosity refers to viscosities greater than 50,000 cst., and especially those greater than 100,000 cst. Reduction in the deposition of the silicone will reduce these negatives, but will also reduce desirable hair conditioning benefits. Thus, a need still exists for improved conditioning performance in shampoo compositions that does not result in buildup leading to reduced volume and dissatisfaction with the cleansing properties of the shampoo.
Additionally, a recently identified unmet consumer need is the ability to deliver sufficient conditioning performance from a shampoo that is optically clear or at least transparent and does not result in a cleaning tradeoff, buildup, or reduced volume of the intended hair style, and is storage stable. Attempts have been made previously to use dispersed droplets of silicone oil deposited on the hair shaft to provide this conditioning. However, these attempts have resulted in either insufficient conditioning, buildup of conditioning agents, reduction of style volume, or product instability in the form of reduced product clarity and/or an unacceptable reduction in shampoo viscosity over time.
It is known in the art that oily cosmetic agents such as silicones can be incorporated into cosmetic compositions by means of microemulsification, whereby the silicone is present as stably emulsified droplets of a particle size of about 0.15 microns or less.
However, by the very nature of the form in which microemulsified particles of a conditioning oil are incorporated into cosmetic compositions, the conditioning benefits attainable are frequently limited, owing to a poor level of deposition on the intended site, ie. the hair or the skin. Even if sufficient deposition is accomplished, it often results in decreased cleansing, product build up and/or decreased volume. Additionally, storage stability issues such as a significant reduction in product clarity and/or viscosity over time are common with this approach.
Additionally, attempts have been made in the art to use higher internal phase viscosity (>50,000 cst) silicones to provide clear conditioning shampoos. The use of these high viscosity materials presents several technical challenges. The main technical challenges are the reduced cleaning, product buildup, and reduced volume described above. Additionally, attempts have been made to use lower internal phase viscosity (15,000 cst) silicones to provide clear conditioning shampoos. In the past, the use of lower viscosity materials had resulted in conditioning performance tradeoffs and/or viscosity stability tradeoffs. The lack of conditioning performance is likely the result of the inappropriate combination of polymer and surfactant system resulting in poor silicone deposition. Additionally, these attempts have resulted in formulations which are very unstable, showing a significant drop in shampoo viscosity over a relatively short period of time.
Accordingly the need remains for a substantially clear shampoo composition, which delivers superior conditioning benefits to hair and/or skin. The need also remains for a substantially clear shampoo composition, which remains stable/substantially clear after prolonged storage.